CUTANEOUS CYTOLOGY
When do I do it?
- When bacterial or yeast infection is suspected (inflammatory alopecia, seborrhea, scales, papule, pustule, crust, erosions, ulcer)
- In patients with nodule/tumors- do cytology on every nodule/tumor
- In patients with suspected pemphigoid diseases (erosions, pustule, crust)
- In every patient with otitis externa
What can I find?
- Cocci (most likely Staphylococcus sp.)
- Rods → culture and susceptibility advisable
- Inflammatory cells with intracellular bacteria → clinically relevant infection that may require systemic antibiotic treatment
- Eosinophils → can point to ectoparasites or allergies
- Macrophages → seen in chronic, sterile and infectious processes
- Malassezia spp. → one or more Malassezia sp. per oil immersion field (x 1000 magnification) may be clinically relevant (normal numbers vary can vary with the climate.) In cases of Malassezia hypersensitivity a much lower number of Malassezia (e.g. one in every two or three HPFs) can cause clinical disease. Topical or systemic treatment should be considered.
- Neoplastic cells
What do I need?
- Slides, DiffQuick® or similar stain, mineral oil, adhesive tape, microscope, needle and syringe
How do I do it?
- Rub or impress a slide on moist, exuding or greasy surface of infected skin.
- Role a cotton bud on the skin surface or insert it in the ears and role cotton bud on the slide.
- Insert needle (25 - 27 ga.) into the pustule holding the needle parallel to the skin so that only the pustule is punctured, no deeper cells or blood are required, top is lifted off and slide impressed onto the ruptured pustule.
- Use the sticky surface of the adhesive tape to collect cells and surface organisms from dry and / or scaly skin and then place this (sticky side down) onto a glass slide with a drop of the blue Difff-Quick® stain. The tape acts as its own coverslip.
- Apply a piece of double-sided adhesive tape to a slide and collect material with the sticky slide. Stain this in the blue Diff-Quick® stain, dry and examine under oil immersion.
- Insert needle into nodule or abscesses and re-insert a number of times without leaving the skin. Withdraw the needle. A syringe with the plunger pulled back is attached to the needle and contents is blown onto a slide and air dried.
- Stain the air dried slides (e.g. Diff-Quick®)
- Put the slides under a microscope, condenser up.
Tip
- Moisten a cotton bud with saline solution or carefully rub the edge of a slide on the skin and then rub the material on the slide
- Press clear adhesive tape (sticky side down) onto the skin. Stain the tape like a slide, let it air dry and press it onto a slide or put a drop of the blue stain o DiffQuick® on a slide and press the tape sticky side down on the drop. Evaluate under a microscope.
abscess
A discrete swelling containing purulent material, typically in the subcutis
alopecia
Absence of hair from areas where it is normally present; may be due to folliculitis, abnormal follicle cycling, or self-trauma
alopecia (“moth-eaten”)
well-circumscribed, circular, patchy to coalescing alopecia, often associated with folliculitis
angioedema
Regional subcutaneous edema
annular
Ring-like arrangement of lesions
atrophy
Thinning of the skin or other tissues
bulla
Fluid-filled elevation of epidermis, >1cm
hemorrhagic bullae
Blood-filled elevation of epidermis, >1cm
comedo
dilated hair follicle filled with keratin, sebum
crust
Dried exudate and keratinous debris on skin surface
cyst
Nodule that is epithelial-lined and contains fluid or solid material.
depigmentation
Extensive loss of pigment
ecchymoses
Patches due to hemorrhage >1cm
epidermal collarettes
Circular scale or crust with erythema, associated with folliculitis or ruptured pustules or vesicles
erosion
Defect in epidermis that does not penetrate basement membrane. Histopathology may be needed to differentiate from ulcer.
erythema
Red appearance of skin due to inflammation, capillary congestion
eschar
Thick crust often related to necrosis, trauma, or thermal/chemical burn
excoriation
Erosions and/or ulcerations due to self-trauma
fissure
Excessive stratum corneum, confirmed via histopathology. This term is often used to describe the nasal planum and footpads.
fistula
Ulcer on skin surface that originates from and is contiguous with tracts extending into deeper, typically subcutaneous tissues
follicular casts
Accumulation of scale adherent to hair shaft
hyperkeratosis
Excessive stratum corneum, confirmed via histopathology. This term is often used to describe the nasal planum and footpads.
hyperpigmentation
Increased melanin in skin, often secondary to inflammation
hypopigmentation
Partial pigment loss
hypotrichosis
Lack of hair due to genetic factors or defects in embryogenesis.
leukoderma
Lack of cutaneous pigment
leukotrichia
Loss of hair pigment
lichenification
Thickening of the epidermis, often due to chronic inflammation resulting in exaggerated texture
macule
Flat lesion associated with color change <1cm
melanosis
Increased melanin in skin, may be secondary to inflammation.
miliary
Multifocal, papular, crusting dermatitis; a descriptive term, not a diagnosis
morbiliform
A erythematous, macular, papular rash; the erythematous macules are typically 2-10 mm in diameter with coalescence to form larger lesions in some areas
nodule
A solid elevation >1cm
onychodystrophy
Abnormal nail morphology due to nail bed infection, inflammation, or trauma; may include: Onychogryphosis, Onychomadesis, Onychorrhexis, Onychoschizia
onychogryphosis
Abnormal claw curvature; secondary to nail bed inflammation or trauma
onychomadesis
Claw sloughing due to nail bed inflammation or trauma
onychorrhexis
Claw fragmentation due to nail bed inflammation or trauma
onychoschizia
Claw splitting due to nail bed inflammation or trauma
papule
Solid elevation in skin ≤1cm
papules
Solid elevation in skin ≤1cm
paronychia
Inflammation of the nail fold
patch
Flat lesion associated with color change >1cm
petechiae
Small erythematous or violaceous lesions due to dermal bleeding
phlebectasia
Venous dilation; most commonly associated with hypercortisolism
plaques
Flat-topped elevation >1cm formed of coalescing papules or dermal infiltration
pustule
Raised epidermal infiltration of pus
reticulated
Net-like arrangement of lesions
scale
Accumulation of loose fragments of stratum corneum
scar
Fibrous tissue replacing damaged cutaneous and/or subcutaneous tissues
serpiginous
Undulating, serpentine (snake-like) arrangement of lesions
telangiectasia
Permanent enlargement of vessels resulting in a red or violet lesion (rare)
ulcer
A defect in epidermis that penetrates the basement membrane. Histopathology may be needed to differentiate from an erosion.
urticaria
Wheals (steep-walled, circumscribed elevation in the skin due to edema ) due to hypersensitivity reaction
vesicle
Fluid-filled elevation of epidermis, <1cm
wheal
Steep-walled, circumscribed elevation in the skin due to edema